| 1. |
- Liu, Yichao, et al.
(författare)
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Broadband Electromagnetic Wave Tunneling with Transmuted Material Singularity
- 2020
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Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 125:20
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Tidskriftsartikel (refereegranskat)abstract
- Subwavelength channels filled with near-zero-index (NZI) media can realize extraordinary optical functionalities, for example, tunneling electromagnetic wave without reflections, but usually confined in a narrow wavelength band due to the material singularity (refractive index n approximate to 0), which seriously limits the practical potentials. In this Letter, we show this limit can be fundamentally overcome by an alternative, named near-zero-index-featured (NZIF) structure, with the singularity transmuted via a controlled optical conformal mapping, enabling the device implementation with nonmagnetic normal dielectrics (i.e., relative permittivity >1). Their equivalence is strictly examined through a subwavelength tunneling waveguide. Classic wave tunneling features in a broad frequency range are revealed in various confined geometries. These properties are robust against the disturbance of several kinds of structural defects benefited from the infinite effective local wavelength. The broadband and lossless NZIF medium proposed here provides a promising way to pursue the fascinating light controlling functionalities as initially enabled by singular NZI materials.
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| 2. |
- Liu, Yichao, et al.
(författare)
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Fast Adaptive Thermal Buffering by a Passive Open Shell Based on Transformation Thermodynamics
- 2018
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Ingår i: Advanced Theory and Simulations. - : Wiley. - 2513-0390. ; 1:7
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Tidskriftsartikel (refereegranskat)abstract
- By using transformation thermodynamics, an open, adaptive thermal buffer shell (TBS) is designed and experimentally implemented with natural materials (layered copper and expanded polystyrene [EPS]). The TBS can store excessive heat flux quickly in the shell and release it slowly when it is needed, which also has some distinctive features: first it is a buffer shell that can avoid external extremes in temperature (either high or low) and also provide a relatively stable temperature for the interior of the shell when the temperature outside the shell has some fluctuations; second the TBS is not thermally insulated (with holes connected to the outside world) and the buffering effect of the TBS originates from the heat recycling mechanics, not thermal insulation; third the TBS has a short response time and the temperature inside the shell can be quickly adjusted according to the average temperature outside the shell; fourth the TBS is a passive device. Unlike traditional air conditioning, the TBS can work without an external power supply. The TBS will have many applications in energy recycling systems, smart heat controlling systems, and passive heat self-adaptation systems. Numerical simulations and experimental demonstrations are given to verify the function of the TBS.
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| 3. |
- Liu, Yichao, et al.
(författare)
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Novel thermal lens for remote heating/cooling designed with transformation optics
- 2016
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Ingår i: Optics Express. - : Novel thermal lens for remote heating/cooling designed with transformation optics. - 1094-4087. ; 24:6, s. 5683-5692
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Tidskriftsartikel (refereegranskat)abstract
- Remote thermal focusing/refrigeration by suppressing thermal diffusion can be achieved with the help of the novel thermal lens proposed in this paper. Our thermal lens is designed using transformation optics, and has several advantages. Firstly, it is a remote controlling device, i.e. the temperature is increased or decreased only in the heat/cold source and the target points, and the temperature in the area between the source and target points is not influenced. Secondly, the heat/cold sources can move freely inside the lens, and hence the focused points outside the lens can be adjusted dynamically. Numerical simulations are given to verify the novel properties (such as thermal focusing effect, remote refrigeration and remote thermal diffusion suppressing) of the proposed device, which cannot be achieved by any other traditional method. (C) 2016 Optical Society of America
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| 4. |
- Liu, Yichao, et al.
(författare)
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Omnidirectional Conformal Cloak Without Geometrical Dispersion
- 2019
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Ingår i: Physical Review Applied. - : American Physical Society. - 2331-7019. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- The phase delay problem of invisibility cloaks designed by optical conformal mapping is referred to the optical path difference between the waves in upper and lower Riemann sheets. As the frequency changes, the phase delay varies accordingly (here, we call it geometrical dispersion), which restricts the cloaks to working only at some discrete frequencies. Here, we solve the phase-delay problem by placing an optically null medium in the lower Riemann sheet. The conformal cloaks designed by using our method have many advantages, such as a continuous working band (no geometrical dispersion), omnidirectionality, robustness under frequency shifts, and no need for any complex materials that are both anisotropic and inhomogeneous. We also design metallic microchannels to realize our cloaks.
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| 5. |
- Sun, Fei, et al.
(författare)
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A Magnifying Glass for Virtual Imaging of Subwavelength Resolution by Transformation Optics
- 2018
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 30:30
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Tidskriftsartikel (refereegranskat)abstract
- Traditional magnifying glasses can give magnified virtual images with diffraction-limited resolution, that is, detailed information is lost. Here, a novel magnifying glass by transformation optics, referred to as a "superresolution magnifying glass" (SMG) is designed, which can produce magnified virtual images with a predetermined magnification factor and resolve subwavelength details (i.e., light sources with subwavelength distances can be resolved). Based on theoretical calculations and reductions, a metallic plate structure to produce the reduced SMG in microwave frequencies, which gives good performance verified by both numerical simulations and experimental results, is proposed and realized. The function of SMG is to create a superresolution virtual image, unlike traditional superresolution imaging devices that create real images. The proposed SMG will create a new branch of superresolution imaging technology.
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| 6. |
- Sun, Fei, et al.
(författare)
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An Acoustic Metamaterial Lens for Acoustic Point-to-Point Communication in Air
- 2019
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Ingår i: Acoustical Physics. - : PLEIADES PUBLISHING INC. - 1063-7710 .- 1562-6865. ; 65:1, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Acoustic metamaterials have become a novel and effective way to control sound waves and design acoustic devices. In this study, we design a 3D acoustic metamaterial lens (AML) to achieve point-to-point acoustic communication in air: any acoustic source (a speaker) in air enclosed by such an AML can produce an acoustic image where the acoustic wave is focused (the field intensity is at a maximum, and the listener can receive the information), while the acoustic field at other spatial positions is low enough that listeners can hear almost nothing. Unlike a conventional elliptical reflective mirror, the acoustic source can be moved around inside our proposed AML. Numerical simulations are given to verify the performance of the proposed AML.
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| 7. |
- Sun, Fei, et al.
(författare)
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Anti-optic-null medium : Achieving the optic-null medium effect by enclosing an air region with relatively low-anisotropy media
- 2016
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Ingår i: PHYSICAL REVIEW B. - 2469-9950. ; 94:4
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Tidskriftsartikel (refereegranskat)abstract
- A so-called anti-optic-null medium (anti-ONM), which can be utilized to cancel the optic-null medium (ONM) and create many novel optical illusions, is introduced and designed by transformation optics (TO). Optical separation illusions can be achieved with an anti-ONM. With the help of the anti-ONM, we can achieve the same optical illusions where ONM is required via a shelled structure filled with low anisotropic medium, which is easier to realize for some novel optical devices designed by TO and optical surface transformation. The special function of the anti-ONM will lead to a new way to design optical devices or simplify the material requirements. Overlapping illusions, and wave-front reshapers are designed to demonstrate the function of the proposed method.
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| 8. |
- Sun, Fei, et al.
(författare)
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Transformation Optics : From Classic Theory and Applications to its New Branches
- 2017
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Ingår i: Laser & Photonics reviews. - : Wiley-VCH Verlagsgesellschaft. - 1863-8880 .- 1863-8899. ; 11:6
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Forskningsöversikt (refereegranskat)abstract
- In the modern world, the ability to manipulate and control electromagnetic waves has greatly changed people's lives. Novel optical and electromagnetic phenomena and devices will lead to new scientific trends and techniques in the future. The exploration of new theories of optical design and new materials for optical engineering has attracted great attention in recent years. Transformation optics (TO) provides a new way to design optical devices with extraordinary predesigned functions such as invisibility cloaks and electromagnetic wormholes. As the development of artificial electromagnetic media (e.g. metamaterials and metasurfaces) progresses, many of these novel optical devices designed by TO have been experimentally demonstrated and used in specific applications. Starting from the basic theory of transformation optics, we review its applications, extensions, new branches and recent developments in this paper.
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| 9. |
- Sun, Jiachen, et al.
(författare)
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Hepatic Fatty Acid Profiles Associated with Exposure to Emerging and Legacy Halogenated Contaminants in Two Harbor Seal Populations across the North Atlantic
- 2022
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 56:3, s. 1830-1840
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Tidskriftsartikel (refereegranskat)abstract
- Fatty acids (FAs) have been extensively used as indicators of foraging ecology in marine mammals, yet their association with exposure to contaminants has rarely been investigated. The present study provided the first characterization of the relationship between hepatic FA profiles and exposure to a suite of contaminants in a sentinel species─the harbor seal (Phoca vitulina)─from the Gulf of Maine and the south coast of Sweden. FA profiles differed in the two seal populations, and the levels of legacy and alternative brominated flame retardants and polyhalogenated carbazoles were significantly elevated in Maine seals. Correlations between individual FAs and multiple flame retardants (FRs) and poly- and perfluoroalkyl substances (PFASs) were found in seals from both populations. Moreover, several FR and PFAS chemicals were significantly associated with the estimated desaturating enzyme activity inferred from the FA profiles. The ratios of poly to monounsaturated FAs (∑PUFAs/∑MUFAs) and those of unsaturated to saturated FAs (∑UFAs/∑SFAs) were significantly associated with HBBZ, PFHxS, or BDE 47 in seals from Maine and Sweden, whereas ∑n – 6/∑n – 3 PUFAs was significantly associated with BDE 154 and 36-CCZ in Swedish and Maine seals, respectively. Our results suggest the lipid metabolism-disrupting potential of these contaminants in marine mammals and warrant continuous biomonitoring and risk assessment, considering the critical role of PUFAs in vital biological processes.
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| 10. |
- Weinstein, John N., et al.
(författare)
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The cancer genome atlas pan-cancer analysis project
- 2013
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:10, s. 1113-1120
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Forskningsöversikt (refereegranskat)abstract
- The Cancer Genome Atlas (TCGA) Research Network has profiled and analyzed large numbers of human tumors to discover molecular aberrations at the DNA, RNA, protein and epigenetic levels. The resulting rich data provide a major opportunity to develop an integrated picture of commonalities, differences and emergent themes across tumor lineages. The Pan-Cancer initiative compares the first 12 tumor types profiled by TCGA. Analysis of the molecular aberrations and their functional roles across tumor types will teach us how to extend therapies effective in one cancer type to others with a similar genomic profile. © 2013 Nature America, Inc. All rights reserved.
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